a. Field of the Invention
The present invention relates to a device and method of production for facilitating an easy-open end for a container.
b. Description of the Background
Full aperture easy-open can ends for food and non-food products have been present in the marketplace for more than 30 years. Nearly all feature a tab, which is formed independently and is riveted on to the container end shell. The material in the shell is scored near the outer diameter of the end so that when the tab is lifted, the tab perforates the score and then the score fractures as the tab is pulled back. Numerous advancements have been made on score design, tab design, protective folds to reduce the risk of cuts to the user, etc. Even so, the basic premise of the design, function and manufacture of conventional easy-open can ends, has remained nearly unchanged for the past quarter century.
Conventional easy-open can ends experience a variety of problems. In many instances, the forces necessary to fracture and propagate or tear the score can be excessive, especially for older consumers. Because this score is a point of structural debility, present designs are forced to attempt to minimize this weakness in order to stand up to processing and distribution. This conflict has resulted in preventing significant progress in reducing fracture and tear forces. These scores are also subject to corrosion in many applications when exposed to the product or environment. In addition to the problems created by the scoring of the can ends, numerous geometrical problems can arise when these containers are utilized in hyper or hypobarometric applications. For example, when cans are vacuum-sealed, the center panel of the container end is pulled inward which thereby forces the tab downwardly. This can make access to the tab difficult in many cases. Similarly, in pressure pack applications where a domed shaped end is required, conventional scoring and tab openings are not suitable.
Many conventional easy-open can ends also require the use of a riveting mechanism to retain the tab in place. These rivets can add considerable time and expense to the manufacturing process and can be sources of corrosion, fractures and leaks. Because basic easy-open end designs are not optimized for strength relative to buckle resistance, they require the use of heavy gauge materials that add to product weight and cost. On most designs used for processed food products, a countersink is required to meet minimal strength requirements. This countersink pushes the score and opening diameter towards the center of the can, often impeding the removal of the food product, especially with products that are semi-solid (like pet food).
The present invention overcomes the disadvantages and limitations of the prior art by providing a container end that can be easily opened and does not rely on a conventional metal tab, riveted onto the end, thereby avoiding the problems and the cost associated with such a tab. The present invention can utilize a traditional can end shell, with a unique design that allows traditional double seaming of the end onto the can body. One embodiment of the present invention utilizes a traditional container end shell with a separate and distinct ring piece that is formed independently and is inserted into a closed loop countersink which is placed on the outer surface of the container end shell. The removal of this ring exerts a force in the countersink area, initiating and proliferating a discontinuity in the container end, thereby creating an opening in the container. Another embodiment functions the same as the first embodiment except the score in the countersink area is first pierced before the discontinuity is proliferated.
The present invention may therefore comprise a method of creating an opening in a closed shell container comprising: creating a closed loop countersink that protrudes inward from the outer surface of the container shell, creating an area of weakness throughout the closed loop on a portion of the countersink to facilitate preferential separation along the area of weakness, placing a semi-toroidal shaped ring within the countersink, the countersink having a depth greater than the radius of the ring, crimping the countersink on at least one lateral surface to a dimension less than the diameter of the ring, between the portion of the countersink that retains the ring and the outer surface of the container shell, to retain the ring within the countersink, removing the ring from within the crimped countersink to effect a change in the material properties throughout the area of weakness on the countersink thereby propagating a discontinuity in the container material and creating the opening in the closed shell container.
The present invention may also comprise a device for creating an opening in a closed shell container comprising: a closed loop countersink that protrudes inward from an outer surface of the container shell, an area of weakness throughout the closed loop on a portion of the countersink that facilitates a preferential separation along the area of weakness, a semi-toroidal shaped ring placed within the countersink, the countersink having a depth greater than the radius of the ring, a crimp to retain the ring within the countersink on at least one lateral surface of the countersink to a dimension less than the diameter of the ring, the crimp located between the portion of the countersink that retains the ring, and the outer surface of the container shell, a rivetless actuator to remove the ring from within the crimped countersink, the removal effecting a change in the material properties throughout the area of weakness on the countersink and create the opening in the closed shell container.
Numerous benefits may be afforded by the disclosed embodiments and include the elimination of conventional rivets or tabs and the problems associated with these parts. By forming the metal around the ring in the countersink area, there will be considerable enhancement of strength with respect to internal pressure and vacuum holding ability, leading to potential reduction or light weighting of metal used. With this invention, fracturing of the score will occur at one or two points at a time. This reduces tear forces on the end as opposed to the process used by conventional ends. This design is also less susceptible to score fractures that can occur during processing or distribution due to pressure on the tab. Also, the ring material can be specified to also act as a seal or protective material over the scored area, thereby preventing corrosion or unintentional opening.
The disclosed embodiments are highly versatile and can be used for instance with pressure packs where a dome can be incorporated inside the countersink area, adding considerably to strength since the dome area can have a of smaller diameter than a full dome on the same diameter end. Thus, the embodiments are more compatible with aftermarket devices to further enhance the ease of opening. The ability to use the removed container end to re-close the container offers a great advantage over conventional containers. This feature is further enhanced with the O-ring type seal produced by embodiments in which the ring is retained on the outer circumference of the removed end. Manufacturing cost benefits are realized since there is a reduction in the material gauge and the elimination of the rivet and tab. These costs are likely to be less than conventional easy-open can ends and could potentially rival the cost of non-easy open ends due to the enhance strength of the design.
Further advantages to the ease of use may be realized with the present invention. Since the inner panel of the can end will be removed without direct contact with fingers, the end should be less prone to cause cuts and abrasions. Furthermore, with the score in the countersink area, the residual material is less and potentially can be protected by the ring, also enhancing safety. By utilizing a large diameter inner panel, a larger aperture opening is possible leading to easier removal of product.